Stabilization of terpene products



' heating a small quantity of Patented Jan. 18, 1944 STABILIZATION TERPENE PRODUCTS Alfred L. Rummelsburg, Wilmington, Del" as ton,

signor to Hercules Powder Company, Wilming- DeL, a corporation of Delaware No Drawing. Application October Serial No. 413,305

. 7 Claims. ((1260-6315) This invention relates to a method for treating oxidized terpene compounds and more perticularlyit relates to a method for rendering stable oxidized terpene compounds which tend to undergo spontaneous exothermic reactions.

In the processing of terpene hydrocarbon fractions and especially in the chemical conversion of such materials to. terpene alcohols there are obtained by-products which chiefly comprise monocyclic terpenehydrocarbons of limited usefulness. It has recently been found that such by-products can be converted to much more useful products by oxidation as with atmospheric oxygen. However, oxidation is accomplished by the formation of highlyunstable materials. These unstable components of the oxidized terpenes tend to undergo spontaneous exothermic reactions upon warming and in some cases a dangerously violent reaction ensues. Their presence has prevented safe practical use of theoxidized terpenes.

It has now been found-in accordance with this be eliminated safely by treatment of the unstable oxidized terpenes by certain catalytic materials. In accordance with this invention unstable oxidized terpenes are subjected to' the action of a catalyst of the group which is known to be capa-., ble of decomposing hydrogen peroxide until unstable components capable of spontaneous exothermic reaction are substantially eliminated, i. e., are reduced to safe proportions such-that the oxidized terpene material may be stored and shipped without danger. The treatment, in gen- -'eral, involves admixture of the .unstable'material and the catalyst,

usually with mild heating-coupled with control of the temperature in the exothermic reaction resulting, until a safely stabilized product is obtained.

The method in accordance with this invention is applicable to oxidizedterpenes or terpene mixtures which are characterized by instability of the type which leads to spontaneous exothermic reaction entirely within the material itself. Instability of this nature is readily determined by material to a temperature of 120 C. and noting whether appreciable evolution of gas occurs or whether a sharp temperature rise indicating an exothermic reaction occurs at the said temperature or during heatingto the said temperature. The method in accordance with t invention is particularly directed to unstable products of this nature which are derived by oxidation with pure or diluted oxygen gas, for example, with air, of monocyclic ,terpene hydrocarbon fractions with a boiling point or boiling range between about 170 C. and about 195 C. Such fractions will usually contain one or more compounds of the group represented by dipentene, limonene, alpha-terpinene, beta-terpinene,terpinolene, l-4 cineol, 1-8 cineol,

etc. The process is especially valuable in the treatment of fractions containing appreciable portions of terpinolene since it has been found that terpinolene is outstanding 'among'terpenes in its ease of oxidation by gaseous oxygen and invention, that the undesired components can also in its tendency to form unstable compounds.

Typical unstable oxidized terpene compounds are those obtained by air-oxidation at, for example, a temperature between about 0 C. and

about 85 C. and especially at temperatures be tween about 30 C. and about C. of such commercial terpene cuts as thoseknown as $01- venol and Bysol. variable quantities the particular terpenes hereinabove mentioned. Bysol is characterized by a content of terpinolene which is usually above about 25%. The product formed by air-oxida-q tion of terpenes or terpene fractions of this nature will, intypical cases, comprise about 15 to about 30% of water-soluble material of anoxygenated terpene character, about 40 to about of steamdistillable fraction consisting mainly of terpene hydrocarbons having boiling points above about C., and about 20 to about 50% of steam distillation residue whichis a.

viscous liquid or semi-liquid relatively rich in oxygen and comprises polymeric terpenic compounds.

Ithas now been found that unstable oxidized monccyclic terpenes are rendered stable by treatment as herein described with any of the cata-' lysts which-are effective in bringing about or accelerating the decomposition of hydrogen peroxide.' This group of catalysts includes, for example, he metals of group V111 of the periodic system of the elements, 1. e., iron, nickel, cobalt, platinum, palladium, rhodium, ruthenium, etc., with platinum'and palladium especially eifective; also included are oxygen compounds, especially oxides, and salts of the group VH1 metals, 1. e., ferric chloride, ferrous chloride, ferrous sulfate, ferrous sulfide, ferrous acetate, cobaltous chloride, and the like; also included are oxygen compounds of the group VII-B metals, notably manganese oxides such as the dioxide and salts containing manganese, i. e., manganese sulfate, manganese acetate, potassium permanganate, etc.; further included are the metals of oxides and salts thereof, silver These materials contain in oupI-B and; and gold with.

' the desired stable oxidized terpene.

such as about of 1% to-about 25% of the terpenic material and will, in most cases, be utilized in a quantity between about 0.2% and about 5% of the weight of the terpenic material.

The treatment will comprise either vigorous agitation to mix the catalyst and the terpenic material or, will comprise passing the terpenic material through a bed of the catalyst. The treatment will be carried out at a temperature between about 30 C. and about 120 C. and preferably will comprise treatment almostentirely within the range between about 70 C. and about 100 C. In most cases, the treatment will involve initial heating which brings about an exothermic reaction. At this point, vigorous agitation is highly desirable and cooling will, inmost cases, 25 p be resorted to to maintain the reaction mixture within the desired range to prevent excessively rapid heat evolution from taking place. After the reaction has quieted down and the heat evolution is slow, the temperature is usually maintained for a time by extemalheating to insure complete elimination of unstable material. In all cases the treatment is continued within the temperature ranges mentioned until components capable of spontaneous exothermic reaction have been reduced to a small safe proportion or have been substantially eliminated.

A convenient manner vof operation involves heating a portion'of the material to be stabilized with the catalyst to the desired range in a vessel with temperature control means and adding increments of material at a rate such that the desiredtemperature is maintained by the reaction.. After all the material has been added, the temperature is maintained, heating if necessary, until unstable material'has been substantially eliminated. The reaction may also be carried out continuously by passing the material to be stabilized with the catalyst through a coil with temperature control jacketing wherein the material is held for the desired length of time within the desired temperature range.

The product may be recovered after stabilization by filtration from solid catalysts or by decantation from aqueous solutions of catalysts where such are employed. Washing with water may be utilized to eliminate all water-soluble catalyst although this is usually unnecessary. It will be appreciated that treatment with water or aqueous solutions tends to eliminate water-soluble components of the oxidized terpenic mixture and in some cases this is not desirable.

The manner in which treatment with the catalysts brings about stabilization is not fully understood but it is believed that higher oxides are probably decomposedwith the aid of the catalysts to materials of loweroxidation representing By-products may in some cases comprise some water and carbon dioxide. It is believed the reaction may'frequently involve ent in the mixture to bring the components to a 55 of the mixture at 15.5 C. rose to 0.993.

oxidation of some unoxidized terpenes or very slightly oxidized terpenes presstabilizes unstable oxidized terpenes with practically a 100% yield since the unstable materials are converted to useful terpenic derivatives simiv lar in nature to stable components of the mixture.

5 Instability may be tested for by heating a sample to 120 C. and noting whether appreciable gas evolution or an exothermic reaction indicated by a rapid temperature rise occurs. Instability may also be tested for by noting the ability of the material to liberate free iodin upon being heated with an acidified alkali metal iodide solution. It is characteristic of unstable products that they liberate iodin under these conditions freely. The stabilized product is incapable of appreciable l5 spontaneous exothermic reaction upon being heated and is also characterized by little or no iodin liberation upon heating with acidified aqueous alkali metal iodides. terized by an iodin liberation value of not above the equivalent of 1.0% hydrogen peroxide.

The method in accordance with this invention is illustrated by the specific embodiments thereof in the following examples.

Example 1 A terpene fraction obtained as a by-product in the hydration of turpentine to form terpineol and consisting of monocyclic terpenes boiling above 170 C., mainly terpinolene, the terpinenes,

and dipentene, with some limonene and cineols,

was oxidized by blowing airtherethrough at a temperature of 50 C. until the specific gravity at.15.5 C. of the mixture rose to 1.027. Theproduct obtained was an unstable light lemon yellow oxidized terpene mixture. One hundred parts by weight of this material and 0.8 part of powdered ferroussulfate (FeSO4.7H2O) were heated at 90 C. for four hours with vigorous agitation. The resulting product was slightly darker than the original material and was found to be stable upon heating to 150 C. in that no exothermic reaction was observed. The iodin liberation value of the product was /a of the similar value of the untreated material. The

catalyst waspermitted to remain in the product.

Example 2 A terpene fraction consisting of monocyclic product was slightly darker than the unstable material started with. The manganese sulfate was not removed ,from the product although where its presence is objectionable it may be removed by water washing. The stabilized product had an iodin liberation value less than of the value before treatment.

Example 3 A terpene fraction consisting of monocyclic terpenes boiling abovev 170 C. and containin chiefiy terpinolene, alpha-, beta-, and gammaterpienes, dipentene, limonenes, with some menthenes, sabinene, 1-4 and 1-8 cineols, was

. oxidized by blowing oxygen through the material at a temperature of 50 C. until the specific grav- It will be characevolve gas products obtained by the modify surface tension ter-soluble portionsare ity at 155 C. rose to of this'product were vigorously agitated with 2 parts of a catalyst containing 0.5% of platinum supported on kieselguhr for live hours while the temperature was gradually increasedsfrom 30 C. to 80 C. The product was then recovered by assuage 0.990. One hundredparts' filtration from. the catalyst. This product had a negligible iodin liberation value and did. not liberate gas or undergo oxygen reaction when heated upto 150 C. 1

Example; Terpinolene was oxidized by subjecting it to oxygen under 40-50 lbs. per square inch pressure at a temperature maintained at50 C. until 'stroy substantially ponents of the oxidized terpenes capable of-supthe terpinolene increased in weight by 25-27%.-

One himdred parts of this unstable oxidized'terpinolene product was vigorously agitated with 5 parts of a catalyst containing 2% of palladium supported on aluminum oxide for four hours during which the temperature was raised from 40 to 85 C. The product so obtained did not and did not undergo exothermic reaction upon being'heated up to 150 C. It had negligible iodin liberation value.

,The stabilized, oxidized, monocyclic terpene method in accordance with thisinvention are useful as solvents in paints and varnishes and may also be utilized to as detergent aids. Wa-

useiul as softeners for' porting a spontaneous exothermic reaction and thereby produce a stable pene compounds. v

4. A process for improving unstable oxidized monocyclic terpenes which comprises subjecting the said oxidized terpenes to the action of a sufficient amount of ferrous sulfate, to destroy substantially all of the unstable components of the oxidized terpenes capable of supporting a sponduce a. stable mixture .pounds.

taneous exothermic reaction and thereby proof oxidized terpene com- 3. A process which comprises subjecting unmixture of oxidized ter- 5. A process for improving unstable oxidized monocyclic terpenes which comprises subjecting the said oxidized terpenes to the action-of a sufiicient amount of ferrous acetate, to destroy substantially all of the unstable components ofthe' oxidized terpenes capable oi supporting a sponpaper, Cellophane, and other Cellophane products. 4 What I claim anddesire to protect by Letters Patent is:

l. A process for improving unstable. oxidized monocyclic terpenes which comprises subjecting the said oxidized terpenes to the action of a sufficient amount of a compound of a group VIII metal selected from the group consisting of the taneous exothermic reaction and thereby produce a stable mixture 6. A process which comprises subjecting unsaturated monocyclic terpenes boiling above to oxidation at a temperature beabout 170C. low about 85 C. until an appreciable rise in specific, gravity and in the weight of the teroxides and salts thereof, to destroy substantially all of the unstable components of the oxidized terpencscapable ofsupporting a spontaneous exothermic reaction and thereby produce a stable mixture of a compound of a group vm metal selected from the group consisting of the oxides and salts thereof at a temperaturebetween about 30 C. and about 120 C... to destroy substantially all of the unstable components of the oxidized terpenes capable of supporting a spontaneous exothermic reaction and thereby produce a stable mixture of oxidized monocyclic terpenes which duce a P unds.

penes has occurred, and then subjecting the oxidized* terpenes amount of ferrous sulfate. to destroy substantially all of the unstable components of the oxiterpenes capable. of supporting a spontaneous 7. A process for improving oxidized I comprises subiecting the said oxidized terpenes to the action ofa sumcient amount 'of cobaltous chloride. to de-' stroy substantially all-oi the unstable components" of the oxidized terpenes capable of supporting a spontaneous. exothermic reaction and t ereby produce astable mixture of oxidized I terpene compounds.

Armani; amnmsnom.

of oxidized terpene compounds.

to the action oh a suflicien't exothermic reaction and thereby pro-y stable mixture of oxidized terpene com- 3 

